This invention relates generally to speed control systems, such as cruise control systems for vehicles and particularly to a novel speed control system that maintains speed within a selected range of speeds while permitting operator control within the selected range.
The prior art is replete with speed control systems for vehicles, ranging from simple governors to preclude speeds beyond a preset maximum to modern cruise control systems where the vehicle speed is maintained within relatively close tolerances to a particular speed that is determined by the operator. Speed governors have seen very limited service. Conventional cruise controls are robot-like in operation and therefore do not appeal to a great many operators.
A great advantage of cruise control systems is that they avoid the possibility of inadvertent speeding, provided one does not use the accelerator pedal. The disadvantage is that the speed setting may not be comfortable for the operator under varying traffic conditions, with the result that the system may need to be continually disengaged and reengaged by the operator to meet changing traffic conditions.
On modern highways, there is often both a maximum and a minimum posted speed limit, since moving too slowly is also quite dangerous on such roads. It would be of benefit to have a speed control system that would automatically maintain a vehicle speed within a predetermined range of speeds while still permitting operator control of the vehicle speed within the range.
In accordance with the present invention, a plurality of preset speed ranges or windows are provided, one of which may be selected by the operator. Alternatively, the operator may determine a customized speed range or window within which the vehicle speed may be controlled normally with the accelerator pedal. In practice, the speed control system is not engaged until the vehicle has attained a speed corresponding to the lower limit of the selected speed range. Once engaged, the window will not permit vehicle speeds below the lower limit or above the upper limit of the window. Operation of the brake pedal (or turning off the speed control system) immediately disengages the window control and normal operation ensues. Should the operator inadvertently depress the accelerator to an extent that would, under normal conditions, result in a vehicle speed above the established upper limit of the window, the accelerator position is ignored. On the other hand, releasing the accelerator pedal will result in the vehicle speed slowing to the speed corresponding to the established lower limit of the window. In other words, once the vehicle is under window control, the vehicle accelerator pedal is only effective within the window. While the invention is described in connection with a speed control system for a vehicle, it will be appreciated that it is applicable to any device requiring speed control with limited operator intervention. The invention is also not limited to any type of fuel or energy source nor fuel delivery system.